I had Dan Dowling spin me up a 6x47L back around 2005. It was crazy accurate but at first I could not get the velocity to stabilize. Every time I chronographed it I got a different velocity range. I tried all kinds of primers and powders, but found the solution one day while at the range.
In the used brass bucket I spotted some clean looking 22-250 cases, so I grabbed up a hand full of them, went home expanded the necks and ran them through my 6x47 sizing die.
Now I could test the difference between small primers and large primers. The results were definitive.
Well put it this way, I tossed all my small primer Lapua brass in the trash and started making my cases from 6XC brass because it was the closest in size to the 6x47.
If you look at what the pros use, (PRS) there is not one guy near the top who uses a 6x47 and its my understanding that guys think it is fussy and inconsistent. Welcome to the club boys, but the large primer brass did the trick for me.
You boys down south might not notice as much of a problem in the warm weather as I did up here in an Ontario January, but that gun with large primers sure put some gold on the wall.
If you are ok with how yours shoots, that's fine, but if you feel experimental some day, test large primers over a chronograph and I'd be curious to hear what you find, especially over a wide range of temperatures.
BTW, I don't remember my freebore, but I was running 115s at 3000 FPS. If I recall it was a 1:8 twist polygonal barrel from Gary Schneider. I was getting groups around 1/8th MOA at 100 yards. Velocity spread was the lowest I ever saw. I had to turn my chronograph off and on between shots because it kept showing the same number and I thought it didn't catch the shot.